Wat Phra Thaen Sila At Formerly known as Wat Mahathat, it is located on Tao Hill, Ban Phra Taen, Thung Yang Sub-district, close to Wat Phra Yuen Phutthabat Yukon. which is located on the east side on the same hill but different peaks. It is an ancient temple with no evidence of the builder. It was built when the government had brought the stone altar to be enshrined in the seal of Uttaradit province, showing the faith and importance of the stone altar. At present, Wat Phra Thaen Sila At Has been elevated to a third-class royal monastery. Under the Dhammayuth sect in 2006, Phra Thaen Sila At is a Buddhist Chedi, like Phra Thaen Dong Rang. It has been long believe that the Five Lord Buddhas had come to sit on this altar to pray restrain for enlightenment to please animals. It indicates that this altar has a continuous history in Buddhism for a long time. The altar is laterite in a rectangular shape, measuring 8 feet wide, 10 feet long, and 3 feet high. At the base of the altar is decorated with lotus petal patterns. There is also a mondop in Chiang Saen art covered within the viharn of Wat Phra Thaen Sila At. It's been said that the craftsman who built the Viharn of Wat Phra Thaen Sila At, Wat Phra Fang and Wat Suthat is the same person. The old door of the temple is a well-crafted wood carved in several layers overlapping patterns. It is the same pattern as the porch pattern at Wihan Phra Phuttha Chinnarat. It may have been built since the time of King Tilokkarat, the King of the Lanna Kingdom, alongside Somdej Phra Borommarailokanat, the King of Ayutthaya. Later, Phra Borommakot had faith to make a porch door according to the original pattern instead, and then please use that original door to be used as a temple door at Wat Phra Thaen Sila. The door of the old viharn was burned down on March 25. In 1908, a wildfire raged into the temple. That fire left only one cloister where Luang Por Thammachak was enshrined. Later, Phra Yarodom Phakdi Si Uttaradit Nakorn (An Hongsanan), the governor of Uttaradit, raised money to build and repair the viharn. Inside the sanctuary there is a mondop arch covering the altar. Inside the temple grounds there is a “local museum”, initiated by Phra Chalermsilp Chayapaul. In front, there are flowers decorated with herbs garden and a moving museum car converted into a decorated pickup truck attracts the attention of passersby. Inside the museum building (formerly an old sermon hall) decorated in Lanna style, the ground floor has paintings on display. There are photos of history of Wat Phra Thaen Sila At Traditional, Thai dresses and fabrics ,and selling products from the community, the second floor is displaying old Buddha Stuatue, Buddha carved from wood including the lives of villagers in the community. Such as ancient catching tools, kitchen equipment, cups, bowls, pots, jars, knives, basketry livelihood equipment ,and various games. It is open for viewing from 8:00 a.m. - 5:00 p.m. For the altar ceremony, it will be held every day of the 15th waxing moon of the 3rd lunar month or on Makha Bucha Day. annually.